In an apparatus for handling color images, display of images with vivid colors may be preferred. In order to meet with such preference, methods or apparatuses capable of natural enhancement of saturation of video including low-saturation areas have been proposed.
For instance, patent reference 1 discloses a method in which an average saturation value of input video is determined from the color signals of the input video, a saturation enhancement function is determined based on the average saturation value, and the saturation is enhanced.
Also, conventional video display apparatuses have a narrow color reproduction range, and the above-mentioned saturation enhancement has been made to achieve more vivid display of colors within the limited color gamut in which the reproduction is possible. With the expansion of the color reproduction range of the video display apparatuses brought about by advancement of technology in recent years, a greater importance is now attached to refinement in the gradation expression.
Furthermore, by a new standard concerning a video format for diffusion of ultra high definition television, a color gamut wider than the color gamut according to the conventional standard has been stipulated. As a result, a situation is envisaged in which the video signals according to the conventional standard and the video signals according to the new standard are both used.